Question

What human tissues are affected by malaria? What are the main clinical manifestations of the disease?

Answer 1

Malaria has a number of effects on the body. The parasite passes from the blood (where it enters via the bite of an infected mosquito) into the liver, where it reproduces and changes form. After a period of 1-4 weeks (usually – it can be longer) in the liver, the malaria parasite re-enters the blood and begins to infect red blood cells, undoing more reproduction inside the cells and then, in synchrony, bursting out once the cycle is complete. This process of reproduction and destroying red blood cells results in a build-up of toxins and debris in the blood; the resultant immune reaction produces side effects which are the common observable symptoms of malaria, such as fever, chills, nausea and aches.

One particular type of malaria, Plasmodium falciparum, is also able to modify the surface of red blood cells it infects. It causes these cells to become “sticky”, so they lodge in the small blood vessels leading up to major organs. This build-up is called sequestration, and results in reduced blood flow and oxygen deprivation in the organs. When sequestration occurs in the blood vessels in the brain, the patient may experience impaired consciousness, psychological disruption, coma and even death – this manifestation is called “cerebral malaria”.

If diagnosed and treated promptly, the malaria parasites in the blood can usually be killed rapidly and the patient will soon enjoy a complete recovery. With two forms of malaria, P. vivax and P. ovale, the parasite can remain dormant in the liver for months or even years, resulting in relapse of disease at a later date. To prevent this from occurring, patients with these types of malaria can sometimes take primaquine, a drug which kills the liver stages of the malaria parasite as well.

Differential diagnosis:
Malaria can be offered as a differential diagnosis for a big list of diseases.
General: All other causes of fever, migraine, sinusitis, tension headache etc.
Respiratory system: Pharyngitis, bronchitis, pneumonia, bronchopneumonia, pleurisy.
Cardiovascular: Acute myocardial infarction, cardiogenic shock, left ventricular failure, pericarditis

Abdominal: Hepatitis, liver abscess, splenitis, splenic abscess, other causes of splenomegaly, subdiaphragmatic abscess, acute abdomen, cholecystitis, cholangitis, gastroenteritis, amebiasis, appendicitis, etc.
Central nervous system: Acute encephalitis, meningitis, intra-cranial space occupying lesions, stroke, metabolic encephalopathy etc.
Psychiatry: Acute confusional states, acute psychosis, mood disorders
Renal: Acute nephritis, nephrotic syndrome, acute renal failure
Haematological: All other causes of anemia; blood dyscrasias, hemoglobinopathies, hemolytic anemias, intra vascular hemolysis, bleeding diathesis, DIC etc.